Spark-plug



H. J. MUNSTER.

SPARK PLUG.

APPLICATION FILED MAY 22, 1917.

1,336,914. Patented Apr. 13, 1920.

, 'INVENTOR WITNESSES ATTORNEY IIARRY J. MUNSTER, OF SAN DIEGO, CALIFORNIA.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr.- 13, 1920.

Application filed May 22, 1917. Serial No. 170,248.

To (ZZZ whom it may concern;

Be it known that I, HARRY J. MUNSTER, a citizen of the United States, residing at San Diego, in the county of San Diego and State of California, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specification.

This invention relates to spark plugs, and the primary object is to provide an improved construction for spark plugs having electrodes so disposed as to produce an efficient spark, and constructed to obviate the collection of carbon on the terminals of the electrodes.

Another object of the invention is to provide the upper or central electrode of the spark plug with means whereby the oil will drain from the electrode, without contacting with the point of the lower electrode, thus reducing to a minimum the possibility of oil and carbon preventing the production of an intense spark.

A further object of this invention is the provision. of a spark plug which consists of comparatively few parts and is simple.

in construction, but durable and well adapt: ed to withstand the rough usage to which devices of this character are ordinarily subjected.

For a full description of the invention and the advantages and merits thereof, reference is to be had to the following description and the accompanying drawings, wherein is illustrated the preferred form of my invention, in which;

The figure illustrates a spark plug, partly in section disclosing the improved construction contemplated by my invention.

Referring to the drawing, wherein is illustrated the preferred form of my invention, and in which like numerals of reference indicate corresponding parts throughout the several views, the shell 1 and the porcelain insulator 2 may be connected and associated in any manner common to the various types of spark plugs now known in the art. The

central or upper electrode 3 projects downwardly from the lowerend of the insulator 2, and its end is enlarged to provide a substantially dome-shaped terminal 4 which acts as a hood for the end of the lower electrode 5. The face of this hood is concaved as indicated at 6 and, since the outer surface of the hood is curved as shown, it will be obvious that oil collecting on the hood or on the concaved surface will draintoward wardly and outwardly thus preventing the 7 formation of carbon at this particular point. To this extent, it will be obvious, that the electrodes are self-cleaning, and the possibility of formation of carbon is reduced to a minimum thereby assuring a fat and efficient spark at all times.

The lower electrode 5, in order to be. maintained in this position, is secured to the shell 1 in the usual manner and depends downwardly at an angle from which point it is bent upwardly in longitudinal alinement with the upper elect'i de 3, thus bringing the terminal of the lower electrode in position in the recess 7 From the foregoing it will be observed that a very simple and durable spark plug has been provided, the details of which embody the preferred form. I desire it to he understood, however, that slight changes in the minor details of construction may be made without departing from the spirit of the invention or the scope of the claims hereunto appended.

I claim:

A spark plug having a shell and an upper and lower electrode, the terminal of the upper electrode being extended beyond the lower end of the shell and provided with an integral enlarged dome shaped portion having its extreme end face concaved the said dome shaped portion also having a central recess slightly larger than the said lower electrode, the latter having itsterminal extending in longitudinal alinement with the center of the said upper electrode, and projected partially into the said recess and disposed centrally with respect thereto, whereby ane'equal space is provided around the terminal of the lower electrode in the said recess.

In testimony whereof I afiix my signature in presence of two witnesses.

HARRY J. MUNSTER. Witnesses E. B. WILLIAMS, W. E. Avnnnnr'r. 

